At present, in mobile communication, not only voice communication service, but also packet service including Mail and Push, which utilizes mobile communication network functions, are provided for a communication terminal such as a mobile phone in a mobile communication network and a predetermined communication device such as a PDA having communication functions. Moreover, in conventional mobile communication, Web access service is provided for the communication terminal or the predetermined communication device in the mobile communication network through a specific device in the mobile communication network.
Meanwhile, a gateway device has been proposed to connect two different networks. Gateway devices having a protocol conversion function between different networks, an automatic routing function, a screening function, and a relay function for a Push-type service are known. These conventional examples are disclosed in Japanese Patent Application Laid-open No. 11-205370, Japanese Patent Application Laid-open No. 2000-78192, Japanese Patent Application Laid-open No. 2001-69176, Japanese Patent Application Laid-open No. 11-32058, Japanese Patent Application Laid-open No. 2001-159891, and Japanese Patent Application Laid-open No. 2001-168902.
However, the conventional gateway device only performs protocol conversion in a TCP layer as a gateway device to the mobile communication network, and relays packets between the mobile communication network and an IP network. Accordingly, it is necessary to change service in the mobile communication network after passing the gateway device. Thus, it has been impossible to perform processes for changing service in the gateway device.
Moreover, in the conventional mobile communication, service providing devices such as a location information providing device and a charging device are provided for each service. Hence, it has been necessary to change the devices individually upon a service change. Furthermore, information necessary for each service providing device is processed in each service providing device to provide service. Thus, it has been impossible to manage various services integrally.
In addition, the service providing device of the conventional mobile communication network provides service to only a communication terminal or the predetermined communication device of the mobile communication network. Therefore, it has been impossible to utilize functions of the various services in the mobile communication network from a communication terminal or a predetermined communication device of the IP network.